The present invention is directed to methods for predicting or diagnosing a hazelnut-induced systemic reaction, and to methods for preventing or treating such a reaction.
The leading causes of severe food-induced allergic reactions are allergies to peanuts and tree nuts. The prevalence rate for peanut allergy, tree nut allergy, or both is 1.1% in the US population; allergy to tree nuts alone is found in 0.5%. Sicherer et al. (1999) J. Allergy Clin. Immunol. 103:599. Hazelnuts (Corylus avellana) are among the common tree nuts that lead to allergic reactions. In Europe the estimated prevalence of hazelnut allergy is 0.1% to 0.5%. Groot et al. (1996) Allergy 51:712. Allergy to hazelnuts is often found in patients with tree pollen allergy. These patients usually present with oral allergy syndrome caused by cross-reactivity between tree pollen allergens and hazelnut proteins. It has been shown that proteins similar to Cor a 1, the major hazel pollen allergen, and hazel profilin are also expressed in hazelnut and explain the sensitivity to hazelnut in patients allergic to tree pollen. Hirschwehr et al. (1992) J. Allergy Clin. Immunol. 90:927. More recently, a Bet v 1-related major allergen from hazelnut, Cor a 1.0401, has been cloned, expressed, characterized, and compared with the homologue in hazel pollen, Cor a 1.01. Luttkopf et al. (2002) Mol. Immunol. 38:515. On the other hand, severe allergic reactions to hazelnuts are reported in patients without any association to tree pollen allergy. Ortolani et al. (2000) J. Allergy Clin. Immunol. 105:577. These patients usually have urticaria, angioedema, asthma, vomiting, pharyngeal edema, diarrhea, and/or anaphylaxis. Pastorello et al. (2002) J. Allergy Clin. Immunol 109:563 have identified a 9 kD protein in hazelnut that reacted with sera from seven patients with systemic reactions to hazelnut.
The world production of hazelnut has almost doubled in the last two decades, reaching greater than 600,000 tons of in-shell nuts. In the United States 99% of hazelnuts are grown in Oregon, and the main cultivars are Barcelona, occupying 80% of the plantations. Only 10% of the hazelnuts are eaten as in-shell nuts; the majority of the crop is cracked, and the kernels are sold to bakers, candy makers, and other processors. Hazelnuts are commonly found in chocolate, cakes, cookies, breakfast cereals, ice cream, pastries, breads, and confectionery products.
Despite the fact that hazelnuts are used increasingly in the United States and Europe and that allergic reactions are not limited to oral allergy syndrome through cross-reactivity with tree pollen allergens, the identification of hazelnut allergens is still incomplete. By using two-dimensional (2D) proteomics and Edman sequencing, followed by subsequent cloning and sequencing, a new major food allergen involved in the majority of non-tree pollen-associated hazelnut allergy has been identified in accordance with the present invention.